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McCubbin AJ, Irwin C. The effect of pre-exercise oral hyperhydration on endurance exercise performance, heart rate, and thermoregulation: a meta-analytical review. Appl Physiol Nutr Metab 2024; 49:569-583. [PMID: 38198662 DOI: 10.1139/apnm-2023-0384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
This study aimed to determine the effect of pre-exercise hyperhydration on endurance performance (primary outcome), heart rate, thermoregulation, and perceptual responses (secondary outcomes). Six academic databases were searched to February 2023. Only studies reporting differences in hydration between intervention and placebo/control were included. Meta-analysis determined overall effect size (Hedges' g), and meta-regression the influence of independent moderators (ambient temperature, hyperhydration agent, exercise mode, extent of hyperhydration). Overall, 10 publications generating 19 effect estimates for primary outcomes, and 11 publications reporting 48 effect estimates for secondary outcomes, were included. A small-to-moderate improvement in time-to-exhaustion (TTE) (Hedges' g = 0.31, 95% CI: 0.13-0.50, p = 0.001) and time trial (TT) (g = 0.25, 95% CI: 0.002-0.51, p = 0.049) but not total work (TW) tasks (p = 0.120) was found following hyperhydration. No moderating effects were observed. No effect of hyperhydration was found for heart rate following steady state (SS) exercise (p = 0.069) or the performance task (p = 0.072), nor for body temperature post-SS (p = 0.132) or post-performance task (p = 0.349), but meta-regression of sodium versus glycerol showed lower body temperature post-performance task with sodium (g = 0.80, t (5) = 2.65, p = 0.046). No effects were found for perceived exertion or thermal comfort. Study heterogeneity was low, lacking representation of elite and female athletes, and weight-bearing (i.e., running) exercise modalities. These results suggest pre-exercise hyperhydration provides a small-to-moderate benefit to endurance performance in TTE and TT, but not TW performance tasks. While no moderating effects were observed, lack of heterogeneity makes it difficult to generalise these findings.
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Affiliation(s)
- Alan J McCubbin
- Department of Nutrition, Dietetics and Food, Monash University, Notting Hill, Victoria, Australia
| | - Christopher Irwin
- School of Health Sciences and Social Work, Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, Australia
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Tiemeier L, Nikolaidis PT, Chlíbková D, Wilhelm M, Thuany M, Weiss K, Knechtle B. Ultra-Cycling- Past, Present, Future: A Narrative Review. SPORTS MEDICINE - OPEN 2024; 10:48. [PMID: 38679655 PMCID: PMC11056358 DOI: 10.1186/s40798-024-00715-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 04/06/2024] [Indexed: 05/01/2024]
Abstract
BACKGROUND Ultra-endurance events are gaining popularity in multiple exercise disciplines, including cycling. With increasing numbers of ultra-cycling events, aspects influencing participation and performance are of interest to the cycling community. MAIN BODY The aim of this narrative review was, therefore, to assess the types of races offered, the characteristics of the cyclists, the fluid and energy balance during the race, the body mass changes after the race, and the parameters that may enhance performance based on existing literature. A literature search was conducted in PubMed, Scopus, and Google Scholar using the search terms 'ultracycling', 'ultra cycling', 'ultra-cycling', 'ultra-endurance biking', 'ultra-bikers' and 'prolonged cycling'. The search yielded 948 results, of which 111 were relevant for this review. The studies were classified according to their research focus and the results were summarized. The results demonstrated changes in physiological parameters, immunological and oxidative processes, as well as in fluid and energy balance. While the individual race with the most published studies was the Race Across America, most races were conducted in Europe, and a trend for an increase in European participants in international races was observed. Performance seems to be affected by characteristics such as age and sex but not by anthropometric parameters such as skin fold thickness. The optimum age for the top performance was around 40 years. Most participants in ultra-cycling events were male, but the number of female athletes has been increasing over the past years. Female athletes are understudied due to their later entry and less prominent participation in ultra-cycling races. A post-race energy deficit after ultra-cycling events was observed. CONCLUSION Future studies need to investigate the causes for the observed optimum race age around 40 years of age as well as the optimum nutritional supply to close the observed energy gap under consideration of the individual race lengths and conditions. Another research gap to be filled by future studies is the development of strategies to tackle inflammatory processes during the race that may persist in the post-race period.
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Affiliation(s)
- Lucas Tiemeier
- Centre for Rehabilitation & Sports Medicine, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | | | - Daniela Chlíbková
- Centre of Sports Activities, Brno University of Technology, 61669, Brno, Czech Republic
| | - Matthias Wilhelm
- Centre for Rehabilitation & Sports Medicine, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | | | - Katja Weiss
- Institute of Primary Care, University of Zurich, Zurich, Switzerland
| | - Beat Knechtle
- Institute of Primary Care, University of Zurich, Zurich, Switzerland.
- Medbase St. Gallen Am Vadianplatz, Vadianstrasse 26, 9001, St. Gallen, Switzerland.
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3
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Andrade MT, Wanner SP, Santos WME, Mendes TT, Nunes-Leite MMS, de Oliveira GGA, Carmo AAL, Carvalho MV, Silami Garcia E, Soares DD. Ad libitum ice slurry ingestion and half-marathon performance in a hot environment: A study comparing the effects of the amount and moment of ingestion between ice slurry and water at 37 °C. J Therm Biol 2024; 119:103781. [PMID: 38232473 DOI: 10.1016/j.jtherbio.2023.103781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 12/07/2023] [Accepted: 12/21/2023] [Indexed: 01/19/2024]
Abstract
Ice slurry ingestion during prolonged exercises may improve performance in hot environments; however, the ideal amount and timing of ingestion are still uncertain. We determined whether ad libitum ice slurry ingestion influences physiological and perceptual variables and half-marathon performance while comparing the effects of the amount and moment of ingestion between ice slurry and water at 37 °C. Ten trained participants (28 ± 2 years; mean and SD) were required to run two half marathons while consuming either ice slurry (-1 °C; Ad-1) or water (37 °C; 37 CE) ad libitum. They then performed two other half marathons where, during one, they were required to ingest an amount of water equivalent to the amount consumed during the Ad-1 trial (Pro37), and in the other, to ingest ice slurry in the amount consumed during the 37 CE trial (Pro-1). During the half marathons, dry-bulb temperature and relative humidity were controlled at 33.1 ± 0.3 °C and 60 ± 3%, respectively. Ad-1 ingestion (349.6 ± 58.5 g) was 45% less than 37 CE ingestion (635.5 ± 135.8 g). Physical performance, heart rate, perceived exertion, body temperatures, and thermal perception were not influenced by the temperature or amount of beverage ingestion. However, a secondary analysis suggested that lower beverage ingestion was associated with improved performance (Ad-1 + Pro37 vs. 37 CE + Pro-1: -4.0 min, Cohen's d = 0.39), with a significant relationship between lower beverage ingestion and faster running time (b = 0.02, t = 4.01, p < 0.001). In conclusion, ice slurry ingestion does not affect performance or physiological or perceptual variables during a half marathon in a hot environment. Preliminary evidence suggests that lower beverage ingestion (ice slurry or warm water) is associated with improved performance compared to higher ingestion.
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Affiliation(s)
- Marcelo T Andrade
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil; Psychology Program, Belo Horizonte, (MG), Brazil.
| | - Samuel P Wanner
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
| | - Weslley M E Santos
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
| | - Thiago T Mendes
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil; Department of Physical Education, Universidade Federal da Bahia, Salvador, (BA), Brazil
| | - Matheus M S Nunes-Leite
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
| | - Gustavo G A de Oliveira
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
| | - Adriano A L Carmo
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
| | - Moisés V Carvalho
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil; Department of Human Movement Sciences, Universidade Do Estado de Minas Gerais, Ibirité, (MG), Brazil
| | - Emerson Silami Garcia
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
| | - Danusa D Soares
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, (MG), Brazil
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Notley SR, Mitchell D, Taylor NAS. A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 3: Heat and cold tolerance during exercise. Eur J Appl Physiol 2024; 124:1-145. [PMID: 37796292 DOI: 10.1007/s00421-023-05276-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/04/2023] [Indexed: 10/06/2023]
Abstract
In this third installment of our four-part historical series, we evaluate contributions that shaped our understanding of heat and cold stress during occupational and athletic pursuits. Our first topic concerns how we tolerate, and sometimes fail to tolerate, exercise-heat stress. By 1900, physical activity with clothing- and climate-induced evaporative impediments led to an extraordinarily high incidence of heat stroke within the military. Fortunately, deep-body temperatures > 40 °C were not always fatal. Thirty years later, water immersion and patient treatments mimicking sweat evaporation were found to be effective, with the adage of cool first, transport later being adopted. We gradually acquired an understanding of thermoeffector function during heat storage, and learned about challenges to other regulatory mechanisms. In our second topic, we explore cold tolerance and intolerance. By the 1930s, hypothermia was known to reduce cutaneous circulation, particularly at the extremities, conserving body heat. Cold-induced vasodilatation hindered heat conservation, but it was protective. Increased metabolic heat production followed, driven by shivering and non-shivering thermogenesis, even during exercise and work. Physical endurance and shivering could both be compromised by hypoglycaemia. Later, treatments for hypothermia and cold injuries were refined, and the thermal after-drop was explained. In our final topic, we critique the numerous indices developed in attempts to numerically rate hot and cold stresses. The criteria for an effective thermal stress index were established by the 1930s. However, few indices satisfied those requirements, either then or now, and the surviving indices, including the unvalidated Wet-Bulb Globe-Thermometer index, do not fully predict thermal strain.
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Affiliation(s)
- Sean R Notley
- Defence Science and Technology Group, Department of Defence, Melbourne, Australia
- School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- School of Human Sciences, University of Western Australia, Crawley, Australia
| | - Nigel A S Taylor
- Research Institute of Human Ecology, College of Human Ecology, Seoul National University, Seoul, Republic of Korea.
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Andrade MT, Nunes‐Leite MMS, Bruzzi RS, Souza CH, Uendeles‐Pinto JP, Prado LS, Soares DD, Gonçalves DAP, Coimbra CC, Wanner SP. Predicting the body core temperature of recreational athletes at the end of a 10 km self-paced run under environmental heat stress. Exp Physiol 2023; 108:852-864. [PMID: 37018484 PMCID: PMC10988464 DOI: 10.1113/ep091017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 03/14/2023] [Indexed: 04/07/2023]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to identify the factors predicting the body core temperature of athletes at the end of a 10 km self-paced run in a hot environment. What is the main finding and its importance? Hyperthermia in athletes subjected to self-paced running depends on several factors, highlighting the integrated control of core temperature during exercise under environmental heat stress. Five of the seven variables that significantly predicted core temperature are not invasive and, therefore, practical for use outside the laboratory environment: heart rate, sweat rate, wet-bulb globe temperature, running speed and maximal oxygen consumption. ABSTRACT Measurement of body core temperature (Tcore ) is paramount to determining the thermoregulatory strain of athletes. However, standard measurement procedures of Tcore are not practical for extended use outside the laboratory environment. Therefore, determining the factors that predict Tcore during a self-paced run is crucial for creating more effective strategies to minimize the heat-induced impairment of endurance performance and reduce the occurrence of exertional heatstroke. The aim of this study was to identify the factors predicting Tcore values attained at the end of a 10 km time trial (end-Tcore ) under environmental heat stress. Initially, we extracted data obtained from 75 recordings of recreationally trained men and women. Next, we ran hierarchical multiple linear regression analyses to understand the predictive power of the following variables: wet-bulb globe temperature, average running speed, initial Tcore , body mass, differences between Tcore and skin temperature (Tskin ), sweat rate, maximal oxygen uptake, heart rate and change in body mass. Our data indicated that Tcore increased continuously during exercise, attaining 39.6 ± 0.5°C (mean ± SD) after 53.9 ± 7.5 min of treadmill running. This end-Tcore value was primarily predicted by heart rate, sweat rate, differences between Tcore and Tskin , wet-bulb globe temperature, initial Tcore , running speed and maximal oxygen uptake, in this order of importance (β power values corresponded to 0.462, -0.395, 0.393, 0.327, 0.277, 0.244 and 0.228, respectively). In conclusion, several factors predict Tcore in athletes subjected to self-paced running under environmental heat stress. Moreover, considering the conditions investigated, heart rate and sweat rate, two practical (non-invasive) variables, have the highest predictive power.
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Affiliation(s)
- Marcelo T. Andrade
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Matheus M. S. Nunes‐Leite
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Rúbio S. Bruzzi
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Carlos H. Souza
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - João P. Uendeles‐Pinto
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Luciano S. Prado
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
- Sports Training Center, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Danusa D. Soares
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Dawit A. P. Gonçalves
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
- Sports Training Center, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Cândido C. Coimbra
- Laboratory of Endocrinology and Metabolism, Institute of Biological SciencesUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
| | - Samuel P. Wanner
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational TherapyUniversidade Federal de Minas GeraisBelo HorizonteMGBrazil
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Deshayes TA, Pancrate T, Goulet ED. Impact of dehydration on perceived exertion during endurance exercise: A systematic review with meta-analysis. J Exerc Sci Fit 2022; 20:224-235. [PMID: 35601980 PMCID: PMC9093000 DOI: 10.1016/j.jesf.2022.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/09/2022] [Accepted: 03/28/2022] [Indexed: 11/20/2022] Open
Abstract
Background Understanding the impact of stressors on the rating of perceived exertion (RPE) is relevant from a performance and exercise adherence/participation standpoint. Athletes and recreationally active individuals dehydrate during exercise. No attempt has been made to systematically determine the impact of exercise-induced dehydration (EID) on RPE. Objective The present meta-analysis aimed to determine the effect of EID on RPE during endurance exercise and examine the moderating effect of potential confounders. Data analyses Performed on raw RPE values using random-effects models weighted mean effect summaries and meta-regressions with robust standard errors, and with a practical meaningful effect set at 1 point difference between euhydration (EUH) and EID. Only controlled crossover studies measuring RPE with a Borg scale in healthy adults performing ≥30 min of continuous endurance exercise while dehydrating or drinking to maintain EUH were included. Results Sixteen studies were included, representing 147 individuals. Mean body mass loss with EUH was 0.5 ± 0.4%, compared to 2.3 ± 0.5% with EID (range 1.7-3.1%). Within an EID of 0.5-3% body mass, a maximum difference in RPE of 0.81 points (95% CI: 0.36-1.27) was observed between conditions. A meta-regression revealed that RPE increases by 0.21 points for each 1% increase in EID (95% CI: 0.12-0.31). Humidity, ambient temperature and aerobic capacity did not alter the relationship between EID and RPE. Conclusion Therefore, the effect of EID on RPE is unlikely to be practically meaningful until a body mass loss of at least 3%.
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Affiliation(s)
- Thomas A. Deshayes
- Faculty of Physical Activity Sciences, University of Sherbrooke, P.Q., Canada
- Research Center on Aging, University of Sherbrooke, P.Q., Canada
| | - Timothée Pancrate
- Faculty of Physical Activity Sciences, University of Sherbrooke, P.Q., Canada
| | - Eric D.B. Goulet
- Faculty of Physical Activity Sciences, University of Sherbrooke, P.Q., Canada
- Research Center on Aging, University of Sherbrooke, P.Q., Canada
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Bayne F, Racinais S, Mileva KN, Hunter S, Gaoua N. The Type of Per-Cooling Strategies Currently Employed by Competitive and Professional Cyclists-Triathletes During Training and Competition Are Condition (Dry vs. Humid) Dependant. Front Sports Act Living 2022; 4:845427. [PMID: 35694320 PMCID: PMC9174669 DOI: 10.3389/fspor.2022.845427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose To investigate cooling strategies employed by athletes (cyclists-triathletes) during training and competition in hot and dry (HD) and hot and humid (HH) conditions. Methods Thirty-five athletes completed an online questionnaire on the type, timing, and justification of cooling strategies employed during past training and/or competitions in HD and HH conditions. In addition, 3 athletes also completed a one-to-one follow-up interview. Results Comparisons between strategies employed in all conditions were based on N = 14 (40%). Cold-water pouring was the most employed (N = 4; 21%) strategy during training and/or competing in hot conditions. The timing of the strategies employed was based on pitstops only (N = 7; 50%). The justification for strategies employed was based on trial and error (N = 9, 42.85%: N = 10, 47.61%). All athletes rated strategies employed as 1 (“not effective for minimising performance impairments and heat-related illnesses”). Comparisons between HD and HH were based on N = 21 (60%), who employed different strategies based on condition. Cold-water ingestion was the most employed (N = 9, 43%) strategy in HD, whereas a combination of cold-water ingestion and pouring was the most employed (N = 9, 43%) strategy in HH. The timing of strategies employed in the HD split was pre-planned by distance but was modified based on how athletes felt during (N = 8, 38%), and pre-planned by distance and pit stops (N = 8, 38%). The timing of strategies employed in HH was pre-planned based on distance and how athletes felt during (N = 9, 42%). About 57% (N = 12) of the 60% (N = 21) perceived effectiveness in HD and HH as 3 (“Sometimes effective and sometimes not effective”), whereas 43% (N = 9) of the 60% (N = 21) perceived effectiveness in HD and HH as 4 (“Effective for minimising performance impairments”). Conclusion Cold-water ingestion is the preferred strategy by athletes in HD compared to a combination of cold-water ingestion and pouring in HH conditions. All strategies were pre-planned and trialled based on distance and how athletes felt during training and/or competition. These strategies were perceived as effective for minimising performance impairments, but not heat-related illnesses. Future studies should evaluate the effectiveness of these cooling strategies on performance and thermoregulatory responses in HD and HH conditions.
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Affiliation(s)
- Freya Bayne
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
- *Correspondence: Freya Bayne
| | | | - Katya N. Mileva
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
| | - Steve Hunter
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
| | - Nadia Gaoua
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
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Jeker D, Claveau P, Abed MEF, Deshayes TA, Lajoie C, Gendron P, Hoffman MD, Goulet EDB. Programmed vs. Thirst-Driven Drinking during Prolonged Cycling in a Warm Environment. Nutrients 2021; 14:nu14010141. [PMID: 35011016 PMCID: PMC8747324 DOI: 10.3390/nu14010141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/21/2021] [Accepted: 12/24/2021] [Indexed: 11/25/2022] Open
Abstract
We compared the effect of programmed (PFI) and thirst-driven (TDFI) fluid intake on prolonged cycling performance and exercise associated muscle cramps (EAMC). Eight male endurance athletes (26 ± 6 years) completed two trials consisting of 5 h of cycling at 61% V˙O2peak followed by a 20 km time-trial (TT) in a randomized crossover sequence at 30 °C, 35% relative humidity. EAMC was assessed after the TT with maximal voluntary isometric contractions of the shortened right plantar flexors. Water intake was either programmed to limit body mass loss to 1% (PFI) or consumed based on perceived thirst (TDFI). Body mass loss reached 1.5 ± 1.0% for PFI and 2.5 ± 0.9% for TDFI (p = 0.10). Power output during the 20 km TT was higher (p < 0.05) for PFI (278 ± 41 W) than TDFI (263 ± 39 W), but the total performance time, including the breaks to urinate, was similar (p = 0.48) between conditions. The prevalence of EAMC of the plantar flexors was similar between the drinking conditions. Cyclists competing in the heat for over 5 h may benefit from PFI aiming to limit body mass loss to <2% when a high intensity effort is required in the later phase of the race and when time lost for urination is not a consideration.
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Affiliation(s)
- David Jeker
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (D.J.); (P.C.); (M.E.F.A.); (T.A.D.)
| | - Pascale Claveau
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (D.J.); (P.C.); (M.E.F.A.); (T.A.D.)
| | - Mohamed El Fethi Abed
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (D.J.); (P.C.); (M.E.F.A.); (T.A.D.)
| | - Thomas A. Deshayes
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (D.J.); (P.C.); (M.E.F.A.); (T.A.D.)
- Research Center on Aging, University of Sherbrooke, Sherbrooke, QC J1H 4C4, Canada
| | - Claude Lajoie
- Department of Physical Activity Sciences, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (C.L.); (P.G.)
| | - Philippe Gendron
- Department of Physical Activity Sciences, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (C.L.); (P.G.)
| | - Martin D. Hoffman
- Department of Physical Medicine & Rehabilitation, University of California Davis, Sacramento, CA 95817, USA;
- Ultra-Endurance Sports Science & Medicine, Duluth, MN 55811, USA
| | - Eric D. B. Goulet
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (D.J.); (P.C.); (M.E.F.A.); (T.A.D.)
- Research Center on Aging, University of Sherbrooke, Sherbrooke, QC J1H 4C4, Canada
- Correspondence:
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Neuromuscular Activity during Cycling Performance in Hot/Dry and Hot/Humid Conditions. Life (Basel) 2021; 11:life11111149. [PMID: 34833025 PMCID: PMC8623245 DOI: 10.3390/life11111149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/20/2021] [Accepted: 10/20/2021] [Indexed: 11/26/2022] Open
Abstract
To determine the relationships between limiting factors and neuromuscular activity during a self-paced 20-km cycling time trial and evaluate the effect of environmental conditions on fatigue indices. Methods: Ten endurance-trained and heat-acclimated athletes performed in three conditions (ambient temperature, relative humidity): HUMID (30 °C, 90%), DRY (35 °C, 46%) and NEUTRAL (22 °C, 55%). Voluntary muscular contractions and electromagnetic stimulations were recorded before and after the time trials to assess fatigue. The data on performance, temperature, heat storage, electromyogram, heart rate and rating of perceived exertion data were analyzed. Results: Performance was impaired in DRY and HUMID compared with NEUTRAL environment (p < 0.05). The force developed by the vastus lateral muscle during stimulation of the femoral nerve remained unchanged across conditions. The percentage of integrated electromyogram activity, normalized by the value attained during the pre-trial maximal voluntary contraction, decreased significantly throughout the trial only in HUMID condition (p < 0.01). Neuromuscular activity in peripheral skeletal muscle started to fall from the 11th km in HUMID and the 15th km in DRY condition, although core temperature did not reach critical values. Conclusions: These alterations suggest that afferences from core/skin temperature regulate the central neural motor drive, reducing the active muscle recruited during prolonged exercise in the heat in order to prevent the system from hyperthermia.
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Claveau P, Deshayes TA, Jeker D, Pancrate T, Goulet EDB. Provision of instructions to drink ad libitum or according to thirst sensation: impact during 120 km of cycling in the heat in men. Appl Physiol Nutr Metab 2021; 47:1-8. [PMID: 34461024 DOI: 10.1139/apnm-2021-0476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The terms drinking to thirst and ad libitum drinking are used interchangeably, but should they? We investigated the differences in how athletes consumed fluids during exercise when instructed to drink according to thirst or ad libitum. Using a randomized, crossover, and counterbalanced design, 10 males (27 ± 4 y) cycled 120 km (48 ± 4% of peak power, 33 °C, 40% relative humidity) on 2 occasions, while drinking water according to thirst or ad libitum. Participants covered the cycling trials in 222 ± 11 min (p = 0.29). Although the body mass loss at the end of exercise and total volume of water consumed were similar between trials, thirst perception before each sip and the volume consumed per sip were significantly higher with thirst than ad libitum drinking, whereas the total number of sips was significantly lower with thirst than ad libitum drinking. Perceived exertion, rectal temperature, and heart rate were all significantly higher with thirst than ad libitum drinking, but the difference was trivial. In conclusion, thirst and ad libitum drinking are associated with different drinking patterns, but equally maintain fluid balance during prolonged exercise. The terms drinking to thirst and ad libitum drinking can be used interchangeably to guide fluid intake during prolonged exercise. Novelty: Both strategies are associated with different patterns of fluid ingestion during prolonged exercise, but are equally effective in maintaining fluid balance. Perceived exertion, rectal temperature, and heart rate are regulated dissimilarly by thirst and ad libitum drinking, but the difference is trivial.
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Affiliation(s)
- Pascale Claveau
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Thomas A Deshayes
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
- Research Centre on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - David Jeker
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Timothée Pancrate
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Eric D B Goulet
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
- Research Centre on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
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11
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Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 132] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
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Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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12
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He H, Zhang JF, Zhang N, Du S, Liu S, Ma G. The Influence of Fluid Intake Behavior on Cognition and Mood among College Students in Baoding, China. ANNALS OF NUTRITION AND METABOLISM 2021; 76 Suppl 1:63-64. [PMID: 33780928 DOI: 10.1159/000515020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 11/03/2020] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Water is a critical nutrient, and it is important for the maintenance of the physiological function of the human body [<xref ref-type="bibr" rid="ref1">1</xref>-<xref ref-type="bibr" rid="ref3">3</xref>]. In addition to fluid amounts, fluid intake frequency is also important for hydration status [<xref ref-type="bibr" rid="ref4">4</xref>, <xref ref-type="bibr" rid="ref5">5</xref>]. At present, only few guidelines mention fluid intake behavior that recommend drinking water frequently while in small quantities, however, there is no scientific evidence to support it. Therefore, it is necessary to explore the appropriate fluid intake behavior. OBJECTIVE The objective of this study is to evaluate the influence of different fluid intake behavior on cognition and mood, to provide scientific basis for proposing the appropriate fluid intake behavior. METHODS A double-blinded randomized controlled trial was designed and implemented among college students aged 18-23 years in Baoding, China. Subjects were randomly assigned into each of 3 groups using a random number generated by computer software: the subjects consuming plain water 200 mL/2 h, that is, 1,600 mL during whole day (group 1), 100 mL/2 h, that is, 800 mL during whole day (group 2), and 110 mL/1 h, that is, 1,650 mL during whole day (group 3), respectively. Subjects were asked to fast from 11:00 p.m., without consuming any foods or drinks the day before the intervention. From 8:00 a.m. to 10:00 p.m. of the first study day, subjects consumed water according to the instructions and repeated it from 8:00 a.m. to 4:00 p.m. of the second study day. Cognition, mood, and urine osmolality were collected twice at 10:00 a.m. (time 1) and 4:00 p.m. (time 2) of the second study day (shown in Fig. <xref ref-type="fig" rid="f01">1</xref>). RESULTS A total of 92 subjects (46 males, 46 females) completed this study. It was found that the increasing fluid intake amounts lead to an increase in urine output and a decrease in urine osmolality (p < 0.05). Use the mixed models to compare measurements for groups 1 and 2, which showed that when compared with those drinking 800 mL per day, people who drank 1,600 mL per day scored higher in vigor (11.8 vs. 9.1, p < 0.05) and portrait memory test (22.6 vs. 20.8, p < 0.05) but lower in total mood disturbance (90.8 vs. 97.8, p < 0.05). By comparing groups 1 and 3, the results indicated that compared with drinking 8 times per day, people who drank 15 times per day scored lower in portrait memory test (21.8 vs. 22.6, p < 0.05) and hunger (3.3 vs. 3.6, p < 0.05). CONCLUSIONS Reasonable fluid intake behavior may be beneficial to improve the cognition and mood of college students. The fluid intake behavior, which is consuming water 200 mL each time and 8 times per day, is recommended. More studies are needed to advise people to have health-beneficial fluid intake behavior.
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Affiliation(s)
- Hairong He
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, China
| | - Jian Fen Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, China
| | - Na Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, China
| | | | - Shufang Liu
- Health Science Center, Hebei University, Baoding, China
| | - Guansheng Ma
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, China
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He H, Zhang J, Zhang N, Du S, Liu S, Ma G. Effects of the Amount and Frequency of Fluid Intake on Cognitive Performance and Mood among Young Adults in Baoding, Hebei, China: A Randomized Controlled Trial. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17238813. [PMID: 33260939 PMCID: PMC7731196 DOI: 10.3390/ijerph17238813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/23/2020] [Accepted: 11/25/2020] [Indexed: 11/16/2022]
Abstract
Water is a critical nutrient that is important for the maintenance of the physiological function of the human body. This article aimed to investigate the effects of the amount and frequency of fluid intake on cognitive performance and mood. A double-blinded randomized controlled trial was designed and implemented on college students aged 18–23 years in Baoding, China. Participants were randomly assigned into one of three groups: the recommended behavior group (RB group) who drank 200 mL of water every 2 h, the half amount group (HA group) who drank 100 mL of water every 2 h, and the high frequency group (HF group) who drank 110 mL of water every 1 h. The intervention lasted 2 days. Urine osmolality, cognitive performance, and mood of participants in each group were compared using the one-way analysis of variance (ANOVA). A total of 92 participants (46 females, 46 males) completed this study with a completion rate of 95.8%. The urine osmolality of the HA group was higher than that of the RB group and the HF group at two time points (p < 0.05). At time point 1, the scores in the portrait memory test and vigor were statistically different (F = 20.45, p < 0.001; F = 5.46, p = 0.006). It was found that the scores for the portrait memory test in the RB group were lower than those in the HA group and the HF group (p = 0.007; p < 0.001), while the scores of the HF group were higher than those of the HA group (p < 0.001). The scores for vigor in the RB group were significantly higher than those of the HA group (p = 0.006), and they were also significantly higher than those of the HF group (p = 0.004). At time point 2, only the scores for vigor were statistically different (F = 3.80, p = 0.026). It was found that the scores for vigor in the RB group were higher than those in the HA group and HF group (p = 0.018; p = 0.019). Both the amount and frequency of fluid intake may affect urine osmolality and vigor, but these factors have limited impacts on cognitive performance. Rational fluid intake behavior may be beneficial to improve the hydration status and mood of young adults. More research is needed, especially experimental research, to allow causal conclusions to be drawn.
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Affiliation(s)
- Hairong He
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (H.H.); (J.Z.); (N.Z.)
| | - Jianfen Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (H.H.); (J.Z.); (N.Z.)
| | - Na Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (H.H.); (J.Z.); (N.Z.)
| | - Songming Du
- Chinese Nutrition Society, Beijing 100053, China;
| | - Shufang Liu
- Health Science Center, Hebei University, Baoding 071000, China;
| | - Guansheng Ma
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (H.H.); (J.Z.); (N.Z.)
- Laboratory of Toxicological Research and Risk Assessment for Food Safety, Peking University, Beijing 100191, China
- Correspondence: ; Tel./Fax: +86-10-8280-5266
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14
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James LJ, Funnell MP, James RM, Mears SA. Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research. Sports Med 2020; 49:103-114. [PMID: 31696453 PMCID: PMC6901416 DOI: 10.1007/s40279-019-01188-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The impact of alterations in hydration status on human physiology and performance responses during exercise is one of the oldest research topics in sport and exercise nutrition. This body of work has mainly focussed on the impact of reduced body water stores (i.e. hypohydration) on these outcomes, on the whole demonstrating that hypohydration impairs endurance performance, likely via detrimental effects on a number of physiological functions. However, an important consideration, that has received little attention, is the methods that have traditionally been used to investigate how hypohydration affects exercise outcomes, as those used may confound the results of many studies. There are two main methodological limitations in much of the published literature that perhaps make the results of studies investigating performance outcomes difficult to interpret. First, subjects involved in studies are generally not blinded to the intervention taking place (i.e. they know what their hydration status is), which may introduce expectancy effects. Second, most of the methods used to induce hypohydration are both uncomfortable and unfamiliar to the subjects, meaning that alterations in performance may be caused by this discomfort, rather than hypohydration per se. This review discusses these methodological considerations and provides an overview of the small body of recent work that has attempted to correct some of these methodological issues. On balance, these recent blinded hydration studies suggest hypohydration equivalent to 2–3% body mass decreases endurance cycling performance in the heat, at least when no/little fluid is ingested.
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Affiliation(s)
- Lewis J James
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
| | - Mark P Funnell
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
| | - Ruth M James
- Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Stephen A Mears
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
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15
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Abstract
The Ironman is one of the most popular triathlon events in the world. Such a race involves a great number of tactical decisions for a healthy finish and best performance. Dehydration is widely postulated to decrease performance and is known as a cause of dropouts in Ironman. Despite the importance of hydration status after an Ironman triathlon, there is a clear lack of review and especially meta-analysis studies on this topic. Therefore, the objective was to systematically review the literature and carry out a meta-analysis investigating the hydration status after an Ironman triathlon. We conducted a systematic review of the literature up to June 2016 that included the following databases: PubMed, SCOPUS, Science Direct and Web of Science. From the initial 995 references, we included 6 studies in the qualitative analysis and in the meta-analysis. All trials had two measures of hydration status after a full Ironman race. Total body water, blood and urine osmolality, urine specific gravity and sodium plasma concentration were considered as hydration markers. Three investigators independently abstracted data on the study design, sample size, participants’ and race characteristics, outcomes, and quantitative data for the meta-analysis. In the pooled analysis, it seems that the Ironman event led to a moderate state of dehydration in comparison to baseline values (SMD 0.494; 95% CI 0.220 to 0.767; p = 0.001). Some evidence of heterogeneity and consistency was also observed: Q = 19.6; I2 = 28.5%; τ2 = 2.39. The results suggest that after the race athletes seem to be hypo-hydrated in comparison to baseline values.
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16
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Effect of Thirst-Driven Fluid Intake on 1 H Cycling Time-Trial Performance in Trained Endurance Athletes. Sports (Basel) 2019; 7:sports7100223. [PMID: 31615028 PMCID: PMC6835292 DOI: 10.3390/sports7100223] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/01/2019] [Accepted: 10/08/2019] [Indexed: 11/16/2022] Open
Abstract
A meta-analysis demonstrated that programmed fluid intake (PFI) aimed at fully replacing sweat losses during a 1 h high-intensity cycling exercise impairs performance compared with no fluid intake (NFI). It was reported that thirst-driven fluid intake (TDFI) may optimize cycling performance, compared with when fluid is consumed more than thirst dictates. However, how TDFI, compared with PFI and NFI, impacts performance during a 1 h cycling time-trial performance remains unknown. The aim of this study was to compare the effect of NFI, TDFI and PFI on 1 h cycling time-trial performance. Using a randomized, crossover and counterbalanced protocol, 9 (7 males and 2 females) trained endurance athletes (30 ± 9 years; Peak V · O2∶ 59 ± 8 mL·kg-1·min-1) completed three 1 h cycling time-trials (30 °C, 50% RH) with either NFI, TDFI or PFI designed to maintain body mass (BM) at ~0.5% of pre-exercise BM. Body mass loss reached 2.9 ± 0.4, 2.2 ± 0.3 and 0.6 ± 0.2% with NFI, TDFI and PFI, respectively. Heart rate, rectal and mean skin temperatures and ratings of perceived exertion and of abdominal discomfort diverged marginally among trials. Mean distance completed (NFI: 35.6 ± 1.9 km; TDFI: 35.8 ± 2.0; PFI: 35.7 ± 2.0) and, hence, average power output maintained during the time-trials did not significantly differ among trials, and the impact of both PFI and TDFI vs. NFI was deemed trivial or unclear. These findings indicate that neither PFI nor TDFI are likely to offer any advantage over NFI during a 1 h cycling time-trial.
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17
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Alhadad SB, Tan PMS, Lee JKW. Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis. Front Physiol 2019; 10:71. [PMID: 30842739 PMCID: PMC6391927 DOI: 10.3389/fphys.2019.00071] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 01/21/2019] [Indexed: 11/26/2022] Open
Abstract
Background: A majority of high profile international sporting events, including the coming 2020 Tokyo Olympics, are held in warm and humid conditions. When exercising in the heat, the rapid rise of body core temperature (Tc) often results in an impairment of exercise capacity and performance. As such, heat mitigation strategies such as aerobic fitness (AF), heat acclimation/acclimatization (HA), pre-exercise cooling (PC) and fluid ingestion (FI) can be introduced to counteract the debilitating effects of heat strain. We performed a meta-analysis to evaluate the effectiveness of these mitigation strategies using magnitude-based inferences. Methods: A computer-based literature search was performed up to 24 July 2018 using the electronic databases: PubMed, SPORTDiscus and Google Scholar. After applying a set of inclusion and exclusion criteria, a total of 118 studies were selected for evaluation. Each study was assessed according to the intervention's ability to lower Tc before exercise, attenuate the rise of Tc during exercise, extend Tc at the end of exercise and improve endurance. Weighted averages of Hedges' g were calculated for each strategy. Results: PC (g = 1.01) was most effective in lowering Tc before exercise, followed by HA (g = 0.72), AF (g = 0.65), and FI (g = 0.11). FI (g = 0.70) was most effective in attenuating the rate of rise of Tc, followed by HA (g = 0.35), AF (g = −0.03) and PC (g = −0.46). In extending Tc at the end of exercise, AF (g = 1.11) was most influential, followed by HA (g = −0.28), PC (g = −0.29) and FI (g = −0.50). In combination, AF (g = 0.45) was most effective at favorably altering Tc, followed by HA (g = 0.42), PC (g = 0.11) and FI (g = 0.09). AF (1.01) was also found to be most effective in improving endurance, followed by HA (0.19), FI (−0.16) and PC (−0.20). Conclusion: AF was found to be the most effective in terms of a strategy's ability to favorably alter Tc, followed by HA, PC and lastly, FI. Interestingly, a similar ranking was observed in improving endurance, with AF being the most effective, followed by HA, FI, and PC. Knowledge gained from this meta-analysis will be useful in allowing athletes, coaches and sport scientists to make informed decisions when employing heat mitigation strategies during competitions in hot environments.
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Affiliation(s)
- Sharifah Badriyah Alhadad
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
| | - Pearl M S Tan
- Defence Medical & Environmental Research Institute, DSO National Laboratories, Singapore, Singapore
| | - Jason K W Lee
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Defence Medical & Environmental Research Institute, DSO National Laboratories, Singapore, Singapore.,Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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18
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Impact of Ad Libitum Versus Programmed Drinking on Endurance Performance: A Systematic Review with Meta-Analysis. Sports Med 2019; 49:221-232. [DOI: 10.1007/s40279-018-01051-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Abstract
The health and performance of ultra-endurance athletes is dependent on avoidance of performance limiting hypohydration while also avoiding the potentially fatal consequences of exercise-associated hyponatremia due to overhydration. In this work, key factors related to maintaining proper hydration during ultra-endurance activities are discussed. In general, proper hydration need not be complicated and has been well demonstrated to be achieved by simply drinking to thirst and consuming a typical race diet during ultra-endurance events without need for supplemental sodium. As body mass is lost from oxidation of stored fuel, and water supporting the intravascular volume is generated from endogenous fuel oxidation and released with glycogen oxidation, the commonly promoted hydration guidelines of avoiding body mass losses of >2% can result in overhydration during ultra-endurance activities. Thus, some body mass loss should occur during prolonged exercise, and appropriate hydration can be maintained by drinking to the dictates of thirst.
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20
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Abstract
In humans, thirst tends to be alleviated before complete rehydration is achieved. When sweating rates are high and ad libitum fluid consumption is not sufficient to replace sweat losses, a cumulative loss in body water results. Body mass losses of 2% or greater take time to accumulate. Dehydration of ≥ 2% body mass is associated with impaired thermoregulatory function, elevated cardiovascular strain and, in many conditions (e.g., warmer, longer, more intense), impaired aerobic exercise performance. Circumstances where planned drinking is optimal include longer duration activities of > 90 min, particularly in the heat; higher-intensity exercise with high sweat rates; exercise where performance is a concern; and when carbohydrate intake of 1 g/min is desired. Individuals with high sweat rates and/or those concerned with exercise performance should determine sweat rates under conditions (exercise intensity, pace) and environments similar to that anticipated when competing and tailor drinking to prevent body mass losses > 2%. Circumstances where drinking to thirst may be sufficient include short duration exercise of < 1 h to 90 min; exercise in cooler conditions; and lower-intensity exercise. It is recommended to never drink so much that weight is gained.
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Affiliation(s)
- Robert W Kenefick
- Thermal and Mountain Medicine Division, US Army Research Institute, Natick, MA, USA.
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21
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Ad libitum drinking adequately supports hydration during 2 h of running in different ambient temperatures. Eur J Appl Physiol 2018; 118:2687-2697. [PMID: 30267225 DOI: 10.1007/s00421-018-3996-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 09/18/2018] [Indexed: 01/06/2023]
Abstract
PURPOSE To examine if ad libitum drinking will adequately support hydration during exertional heat stress. METHODS Ten endurance-trained runners ran for 2 h at 60% of maximum oxygen uptake under different conditions. Participants drank water ad libitum during separate trials at mean ambient temperatures of 22 °C, 30 °C and 35 °C. Participants also completed three trials at a mean ambient temperature of 35 °C while drinking water ad libitum in all trials, and with consumption of programmed glucose or whey protein hydrolysate solutions to maintain euhydration in two of these trials. Heart rate, oxygen uptake, rectal temperature, perceived effort, and thermal sensation were monitored, and nude body mass, hemoglobin, hematocrit, and plasma osmolality were measured before and after exercise. Water and mass balance equations were used to calculate hydration-related variables. RESULTS Participants adjusted their ad libitum water intake so that the same decrease in body mass (1.1-1.2 kg) and same decrease in body water (0.8-0.9 kg) were observed across the range of ambient temperatures which yielded significant differences (p < .001) in sweat loss. Overall, water intake and total water gain replaced 57% and 66% of the water loss, respectively. The loss in body mass and body water associated with ad libitum drinking resulted in no alteration in physiological and psychophysiological variables compared with the condition when hydration was nearly fully maintained (0.3 L body water deficit) relative to pre-exercise status from programmed drinking. CONCLUSIONS Ad libitum drinking is an appropriate strategy for supporting hydration during running for 2 h duration under hot conditions.
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22
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Goulet EDB. Comment on "Drinking Strategies: Planned Drinking Versus Drinking to Thirst''. Sports Med 2018; 49:631-633. [PMID: 30094801 DOI: 10.1007/s40279-018-0973-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Eric D B Goulet
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada. .,Research Centre on Aging, University of Sherbrooke, Sherbrooke, QC, Canada. .,Performance, Hydration and Thermoregulation Laboratory, University of Sherbrooke, 2500 boul. de l'Université, Sherbrooke, QC, J1K 2R1, Canada.
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23
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Hoffman MD, Stellingwerff T, Costa RJS. Considerations for ultra-endurance activities: part 2 - hydration. Res Sports Med 2018; 27:182-194. [PMID: 30056755 DOI: 10.1080/15438627.2018.1502189] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
It is not unusual for those participating in ultra-endurance (> 4 hr) events to develop varying degrees of either hypohydration or hyperhydration. Yet, it is important for ultra-endurance athletes to avoid the performance limiting and potentially fatal consequences of these conditions. During short periods of exercise (< 1 hr), trivial effects on the relationship between body mass change and hydration status result from body mass loss due to oxidation of endogenous fuel stores, and water supporting the intravascular volume being generated from endogenous fuel oxidation and released with glycogen oxidation. However, these effects have meaningful implications during prolonged exercise. In fact, body mass loses well over 2% may be required during some ultra-endurance activities to avoid hyperhydration. Therefore, the typical hydration guidelines to avoid more than 2% body mass loss do not apply in ultra-endurance activities and can potentially result in hyperhydration. Fortunately, achieving the balance of proper hydration during ultra-endurance activities need not be complicated and has been well demonstrated to generally be achieved by simply drinking to thirst and avoiding excessive sodium supplementation with intention of replacing all sodium losses during the exercise.
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Affiliation(s)
- Martin D Hoffman
- a Physical Medicine and Rehabilitation Service, Department of Veterans Affairs , Northern California Health Care System , Sacramento , CA , USA.,b Department of Physical Medicine and Rehabilitation , University of California Davis Medical Center , Sacramento , CA , USA.,c Ultra Sports Science Foundation , El Dorado Hills , CA , USA
| | | | - Ricardo J S Costa
- e Department of Nutrition Dietetics and Food , Monash University , Notting Hill , Victoria , Australia
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Kenefick RW. Author's Reply to Valenzuela et al.: Comment on "Drinking Strategies: Planned Drinking Versus Drinking to Thirst". Sports Med 2018; 48:2215-2217. [PMID: 29582379 DOI: 10.1007/s40279-018-0902-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Robert W Kenefick
- Thermal and Mountain Medicine Division, US Army Research Institute, Natick, MA, USA.
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25
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James LJ, Moss J, Henry J, Papadopoulou C, Mears SA. Hypohydration impairs endurance performance: a blinded study. Physiol Rep 2018. [PMID: 28637708 PMCID: PMC5492205 DOI: 10.14814/phy2.13315] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The general scientific consensus is that starting exercise with hypohydration >2% body mass impairs endurance performance/capacity, but most previous studies might be confounded by a lack of subject blinding. This study examined the effect of hypohydration in a single blind manner using combined oral and intragastric rehydration to manipulate hydration status. After familiarization, seven active males (mean ± SD: age 25 ± 2 years, height 1.79 ± 0.07, body mass 78.6 ± 6.2, VO2peak 48 ± 7 mL·kg·min-1) completed two randomized trials at 34°C. Trials involved an intermittent exercise preload (8 × 15 min exercise/5 min rest), followed by a 15-min all-out performance test on a cycle ergometer. During the preload, water was ingested orally every 10 min (0.2 mL·kg body mass-1). Additional water was infused into the stomach via a gastric feeding tube to replace sweat loss (EU) or induce hypohydration of ~2.5% body mass (HYP). Blood samples were drawn and thirst sensation rated before, during, and after exercise. Body mass loss during the preload was greater (2.4 ± 0.2% vs. 0.1 ± 0.1%; P < 0.001), while work completed during the performance test was lower (152 ± 24 kJ vs. 165 ± 22 kJ; P < 0.05) during HYP At the end of the preload, heart rate, RPE, serum osmolality, and thirst were greater and plasma volume lower during HYP (P < 0.05). These results provide novel data demonstrating that exercise performance in the heat is impaired by hypohydration, even when subjects are blinded to the intervention.
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Affiliation(s)
- Lewis J James
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, United Kingdom
| | - Jodie Moss
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, United Kingdom
| | - Joshua Henry
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, United Kingdom
| | - Charikleia Papadopoulou
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, United Kingdom
| | - Stephen A Mears
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, United Kingdom
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Hayakawa NMM, Reis RCG, Oliveira JPLD, Pereira JDAR, Abreu WCD. Drinking to thirst influences fluid replacement in adolescents judokas. MOTRIZ: REVISTA DE EDUCACAO FISICA 2018. [DOI: 10.1590/s1980-6574201800010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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McDermott BP, Anderson SA, Armstrong LE, Casa DJ, Cheuvront SN, Cooper L, Kenney WL, O'Connor FG, Roberts WO. National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active. J Athl Train 2017; 52:877-895. [PMID: 28985128 PMCID: PMC5634236 DOI: 10.4085/1062-6050-52.9.02] [Citation(s) in RCA: 190] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To present evidence-based recommendations that promote optimized fluid-maintenance practices for physically active individuals. BACKGROUND Both a lack of adequate fluid replacement (hypohydration) and excessive intake (hyperhydration) can compromise athletic performance and increase health risks. Athletes need access to water to prevent hypohydration during physical activity but must be aware of the risks of overdrinking and hyponatremia. Drinking behavior can be modified by education, accessibility, experience, and palatability. This statement updates practical recommendations regarding fluid-replacement strategies for physically active individuals. RECOMMENDATIONS Educate physically active people regarding the benefits of fluid replacement to promote performance and safety and the potential risks of both hypohydration and hyperhydration on health and physical performance. Quantify sweat rates for physically active individuals during exercise in various environments. Work with individuals to develop fluid-replacement practices that promote sufficient but not excessive hydration before, during, and after physical activity.
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Kavouras SA, Bardis CN, Adams J. Response. Med Sci Sports Exerc 2017. [DOI: 10.1249/mss.0000000000001265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Goulet EDB, Gosselin J, Hoffman MD. Improper Assessment of the Effect of Ad Libitum Drinking on Cycling Performance. Med Sci Sports Exerc 2017. [PMID: 28622201 DOI: 10.1249/mss.0000000000001264] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Eric D B Goulet
- Faculty of Physical Activity Sciences Research Centre on Aging University of Sherbrooke Sherbrooke, Quebec, CANADA Faculty of Physical Activity Sciences University of Sherbrooke Sherbrooke, Quebec, CANADA Department of Physical Medicine and Rehabilitation Department of Veterans Affairs Northern California Health Care System and University of California Davis Medical Center Sacramento, CA
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Hoffman MD, Cotter JD, Goulet ÉD, Laursen PB. VIEW: Is Drinking to Thirst Adequate to Appropriately Maintain Hydration Status During Prolonged Endurance Exercise? Yes. Wilderness Environ Med 2017; 27:192-5. [PMID: 27291699 DOI: 10.1016/j.wem.2016.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 03/03/2016] [Accepted: 03/09/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Martin D Hoffman
- Department of Physical Medicine & Rehabilitation Department of Veterans Affairs, Northern California Health Care System, and University of California Davis Medical Center, Sacramento, CA, USA (Dr Hoffman)
| | - James D Cotter
- Exercise and Environmental Physiology, School of Physical Education, Sport and Exercise Sciences Division of Sciences, University of Otago, Dunedin New Zealand (Dr Cotter)
| | - Éric D Goulet
- Research Centre on Aging, Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC Canada (Dr Goulet)
| | - Paul B Laursen
- High Performance Sport New Zealand, and Sports Performance Research Institute New Zealand (SPRINZ) Auckland University of Technology, Auckland New Zealand (Dr Laursen)
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The Influence of Drinking Fluid on Endurance Cycling Performance: A Meta-Analysis. Sports Med 2017; 47:2269-2284. [DOI: 10.1007/s40279-017-0739-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Davies MJ, Clark B, Welvaert M, Skorski S, Garvican-Lewis LA, Saunders P, Thompson KG. Effect of Environmental and Feedback Interventions on Pacing Profiles in Cycling: A Meta-Analysis. Front Physiol 2016; 7:591. [PMID: 27994554 PMCID: PMC5136559 DOI: 10.3389/fphys.2016.00591] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 11/14/2016] [Indexed: 11/15/2022] Open
Abstract
In search of their optimal performance athletes will alter their pacing strategy according to intrinsic and extrinsic physiological, psychological and environmental factors. However, the effect of some of these variables on pacing and exercise performance remains somewhat unclear. Therefore, the aim of this meta-analysis was to provide an overview as to how manipulation of different extrinsic factors affects pacing strategy and exercise performance. Only self-paced exercise studies that provided control and intervention group(s), reported trial variance for power output, disclosed the type of feedback received or withheld, and where time-trial power output data could be segmented into start, middle and end sections; were included in the meta-analysis. Studies with similar themes were grouped together to determine the mean difference (MD) with 95% confidence intervals (CIs) between control and intervention trials for: hypoxia, hyperoxia, heat-stress, pre-cooling, and various forms of feedback. A total of 26 studies with cycling as the exercise modality were included in the meta-analysis. Of these, four studies manipulated oxygen availability, eleven manipulated heat-stress, four implemented pre-cooling interventions and seven studies manipulated various forms of feedback. Mean power output (MPO) was significantly reduced in the middle and end sections (p < 0.05), but not the start section of hypoxia and heat-stress trials compared to the control trials. In contrast, there was no significant change in trial or section MPO for hyperoxic or pre-cooling conditions compared to the control condition (p > 0.05). Negative feedback improved overall trial MPO and MPO in the middle section of trials (p < 0.05), while informed feedback improved overall trial MPO (p < 0.05). However, positive, neutral and no feedback had no significant effect on overall trial or section MPO (p > 0.05). The available data suggests exercise regulation in hypoxia and heat-stress is delayed in the start section of trials, before significant reductions in MPO occur in the middle and end of the trial. Additionally, negative feedback involving performance deception may afford an upward shift in MPO in the middle section of the trial improving overall performance. Finally, performance improvements can be retained when participants are informed of the deception.
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Affiliation(s)
- Michael J Davies
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia
| | - Bradley Clark
- University of Canberra Research Institute for Sport and Exercise Bruce, ACT, Australia
| | - Marijke Welvaert
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia
| | - Sabrina Skorski
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Institute of Sports and Preventive Medicine, Saarland UniversitySaarbrücken, Germany
| | - Laura A Garvican-Lewis
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia; Mary Mackillop Institute for Health Research, Australian Catholic UniversityMelbourne, VIC, Australia
| | - Philo Saunders
- Department of Physiology, Australian Institute of Sport Bruce, ACT, Australia
| | - Kevin G Thompson
- University of Canberra Research Institute for Sport and Exercise Bruce, ACT, Australia
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Adams WM, Hosokawa Y, Belval LN, Huggins RA, Stearns RL, Casa DJ. Deviation from goal pace, body temperature and body mass loss as predictors of road race performance. J Sci Med Sport 2016; 20:302-306. [PMID: 27720128 DOI: 10.1016/j.jsams.2016.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/03/2016] [Accepted: 07/28/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVES The purpose of this study was to examine the relationship between pacing, gastrointestinal temperature (TGI), and percent body mass loss (%BML) on relative race performance during a warm weather 11.3km road race. DESIGN Observational study of a sample of active runners competing in the 2014 Falmouth Road Race. METHODS Participants ingested a TGI pill and donned a GPS enabled watch with heart rate monitoring capabilities prior to the start of the race. Percent off predicted pace (%OFF) was calculated for seven segments of the race. Separate linear regression analyses were used to assess the relationship between pace, TGI, and %BML on relative race performance. One-way ANOVA was used to analyse post race TGI (≥40°C vs <40°C) on pace and %OFF. RESULTS Larger %BML was associated with faster finish times (R2=0.19, p=0.018), faster average pace (R2=0.29, p=0.012), and a greater %OFF (R2=0.15, p=0.033). %OFF during the first mile (1.61km) significantly predicted overall finish time (R2=0.64, p<0.001) while %OFF during the second mile (3.22km) (R2 change=0.18, p<0.001) further added to the model (R2=0.82, p<0.001). Body temperature (pre race TGI and post race TGI) was not predictive of overall finish time (p>0.05). There was a trend in a slower pace (p=0.055) and greater %OFF (p=0.056) in runners finishing the race with a TGI>40°C. CONCLUSIONS Overall, finish time was influenced by greater variations in pace during the first two miles of the race. In addition, runners who minimized fluid losses and had lower TGI were associated with meeting self-predicted goals.
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Affiliation(s)
- William M Adams
- Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology, University of Connecticut, United States.
| | - Yuri Hosokawa
- Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology, University of Connecticut, United States
| | - Luke N Belval
- Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology, University of Connecticut, United States
| | - Robert A Huggins
- Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology, University of Connecticut, United States
| | - Rebecca L Stearns
- Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology, University of Connecticut, United States
| | - Douglas J Casa
- Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology, University of Connecticut, United States
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Thermoregulation During Extended Exercise in the Heat: Comparisons of Fluid Volume and Temperature. Wilderness Environ Med 2016; 27:386-92. [DOI: 10.1016/j.wem.2016.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 06/17/2016] [Accepted: 06/18/2016] [Indexed: 11/21/2022]
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Valentino TR, Stuempfle KJ, Kern M, Hoffman MD. The influence of hydration state on thermoregulation during a 161-km ultramarathon. Res Sports Med 2016; 24:212-21. [PMID: 27258701 DOI: 10.1080/15438627.2016.1191491] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
It is advised that individuals should avoid losing >2% of their body mass during exercise in order to prevent hyperthermia. This study sought to assess whether a loss of >2% body mass leads to elevations in core temperature during an ultramarathon. Thirty runners agreed to take part in the study. Body mass and core temperature were measured at the start, at three locations during the race and the finish. Core temperature was not correlated with percent body mass change (p = 0.19) or finish time (p = 0.11). Percent body mass change was directly associated with finish time (r = 0.58, p < 0.01), such that the fastest runners lost the most mass (~3.5-4.0%). It appears that a loss of >3% body mass does not contribute to rises in core temperature. An emphasis on fluid replacement for body mass losses of this magnitude during prolonged exercise is not justified as a preventative measure for heat-related illnesses.
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Affiliation(s)
- Taylor R Valentino
- a Department of Kinesiology , San Francisco State University , San Francisco , CA , USA
| | | | - Marialice Kern
- a Department of Kinesiology , San Francisco State University , San Francisco , CA , USA
| | - Martin D Hoffman
- c Department of Physical Medicine & Rehabilitation, Department of Veterans Affairs , Northern California Health Care System, and University of California Davis Medical Center , Sacramento , CA , USA.,d Department of Physical Rehabilitation , Sarcomento VA Medical Center , Sacromento , CA , USA
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Kenefick RW, Cheuvront SN. Physiological adjustments to hypohydration: Impact on thermoregulation. Auton Neurosci 2016; 196:47-51. [PMID: 26944095 DOI: 10.1016/j.autneu.2016.02.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/04/2016] [Accepted: 02/07/2016] [Indexed: 11/25/2022]
Abstract
Sufficient body water is required to sustain thermoregulatory function, thus losses in total body water (TBW) can challenge the thermoregulatory system. A TBW deficit ≥2% body mass (hypohydration) is recognized as the threshold when thermoregulatory function becomes measurably altered. Hypohydration may occur from voluntary fluid restriction, insufficient fluid availability, or thermoregulatory sweating. The secretion and evaporation of sweat important avenues of body heat loss, and if the water lost is not replaced, hypohydration will decrease plasma volume and increase plasma osmotic pressure (hyperosmotic hypovolemia). Both osmotic and/or volume stressors delay the onset and/or reduce the sensitivity of sweating and blood flow responses. The magnitude of hypohydration, environmental heat stress, the population and circumstances of interest will determine the degree, significance and outcome of these thermoregulatory alterations and their contribution to physiological stress.
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Affiliation(s)
- Robert W Kenefick
- U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, United States.
| | - Samuel N Cheuvront
- U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, United States
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Skorski S, Hammes D, Schwindling S, Veith S, Pfeiffer M, Ferrauti A, Kellmann M, Meyer T. Effects of training-induced fatigue on pacing patterns in 40-km cycling time trials. Med Sci Sports Exerc 2015; 47:593-600. [PMID: 25003772 DOI: 10.1249/mss.0000000000000439] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION In some endurance sports, athletes complete several competitions within a short period, resulting in accumulated fatigue. It is unclear whether fatigued athletes choose the same pacing pattern (PP) as when they have recovered. PURPOSE This study aimed to analyze effects of fatigue on PP of cyclists during a 40-km time trial (TT). METHODS Twenty-three male cyclists (28.8 ± 7.6 yr) completed three 40-km TT on a cycle ergometer. TT were conducted before (TT1) and after (TT2) a 6-d training period. A third TT was carried out after 72 h of recovery (TT3). Training days consisted of two cycling sessions: mornings, 1 h at 95% of lactate threshold or 3 × 5 × 30 s all-out sprint; afternoons, 3 h at 80% individual anaerobic threshold. Four-kilometer split times (min) and RPE were recorded during TT. RESULTS Performance decreased from TT1 to TT2 (65.7 ± 3.5 vs 66.7 ± 3.3 min; P < 0.05) and increased from TT2 to TT3 (66.7 ± 3.3 vs 65.5 ± 3.3 min; P < 0.01). PP showed a significant difference between TT1 and TT2 (P < 0.001) as well as between TT2 and TT3 (P < 0.01). PP in TT1 and TT3 showed no significant difference (P > 0.05). In TT1 and TT3, cyclists started faster in the first 4 km compared with TT2. RPE course showed no significant difference between TT (P > 0.05). CONCLUSIONS Fatigue reversibly changes the PP of cyclists during a 40-km TT. Participants reduced their power output until premature exhaustion seemed very unlikely. This supports the assumption that pacing includes a combination of anticipation and feedback mechanisms.
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Affiliation(s)
- Sabrina Skorski
- 1Institute of Sports and Preventive Medicine, Saarland University, Saarbrücken, GERMANY; 2Institute of Sports Science, Johannes-Gutenberg University, Mainz, GERMANY; 3Faculty of Sports Science, Ruhr-University of Bochum, Bochum, GERMANY; and 4School of Human Movement Studies and School of Psychology, University of Queensland, Brisbane, Queensland, AUSTRALIA
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Cotter JD, Thornton SN, Lee JK, Laursen PB. Are we being drowned in hydration advice? Thirsty for more? EXTREME PHYSIOLOGY & MEDICINE 2014; 3:18. [PMID: 25356197 PMCID: PMC4212586 DOI: 10.1186/2046-7648-3-18] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/01/2014] [Indexed: 12/29/2022]
Abstract
Hydration pertains simplistically to body water volume. Functionally, however, hydration is one aspect of fluid regulation that is far more complex, as it involves the homeostatic regulation of total body fluid volume, composition and distribution. Deliberate or pathological alteration of these regulated factors can be disabling or fatal, whereas they are impacted by exercise and by all environmental stressors (e.g. heat, immersion, gravity) both acutely and chronically. For example, dehydration during exercising and environmental heat stress reduces water volume more than electrolyte content, causing hyperosmotic hypohydration. If exercise continues for many hours with access to food and water, composition returns to normal but extracellular volume increases well above baseline (if exercising upright and at low altitude). Repeating bouts of exercise or heat stress does likewise. Dehydration due to physical activity or environmental heat is a routine fluid-regulatory stress. How to gauge such dehydration and - more importantly-what to do about it, are contested heavily within sports medicine and nutrition. Drinking to limit changes in body mass is commonly advocated (to maintain ≤2% reduction), rather than relying on behavioural cues (mainly thirst) because the latter has been deemed too insensitive. This review, as part of the series on moving in extreme environments, critiques the validity, problems and merits of externally versus autonomously controlled fluid-regulatory behaviours, both acutely and chronically. Our contention is that externally advocated hydration policies (especially based on change in body mass with exercise in healthy individuals) have limited merit and are extrapolated and imposed too widely upon society, at the expense of autonomy. More research is warranted to examine whether ad libitum versus avid drinking is beneficial, detrimental or neither in: acute settings; adapting for obligatory dehydration (e.g. elite endurance competition in the heat), and; development of chronic diseases that are associated with an extreme lack of environmental stress.
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Affiliation(s)
- James David Cotter
- Exercise and Environmental Physiology, School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Simon N Thornton
- Faculté de Médecine, Université de Lorraine, U 1116 -INSERM-UL, 9, Avenue de la forêt de Haye, CS50-184 - 54505 VANDŒUVRE, Les Nancy cedex, France
| | - Jason Kw Lee
- Defence Medical and Environmental Research Institute, DSO National Laboratories, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore ; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Paul B Laursen
- High Performance Sport New Zealand, Auckland, New Zealand ; Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
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Armstrong LE, Johnson EC, Kunces LJ, Ganio MS, Judelson DA, Kupchak BR, Vingren JL, Munoz CX, Huggins RA, Hydren JR, Moyen NE, Williamson KH. Drinking to thirst versus drinking ad libitum during road cycling. J Athl Train 2014; 49:624-31. [PMID: 25098657 DOI: 10.4085/1062-6050-49.3.85] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT The sensation of thirst is different from the complex behavior of drinking ad libitum. Rehydration recommendations to athletes differ, depending on the source, yet no previous researchers have systematically compared drinking to thirst (D(TT)) versus ad libitum drinking behavior (D(AL)). OBJECTIVE To compare 2 groups of trained cyclists (D(TT) and D(AL)) who had similar physical characteristics and training programs (P > .05). The D(TT) group (n = 12, age = 47 ± 7 years) drank only when thirsty, whereas the D(AL) group (n = 12, age = 44 ± 7 years) consumed fluid ad libitum (ie, whenever and in whatever volume desired). DESIGN Cohort study. SETTING Road cycling (164 km) in the heat (36.1 °C ± 6.5 °C). PATIENTS OR OTHER PARTICIPANTS Ultraendurance cyclists (4 women, 20 men). INTERVENTION(S) We recorded measurements 1 day before the event, on event day before the start, at 3 roadside aid stations, at the finish line, and 1 day after the event. MAIN OUTCOME MEASURE(S) Body mass, urinary hydration indices, and food and fluids consumed. RESULTS No between-groups differences were seen on event day for total exercise time (DTT = 6.69 ± 0.89 hours, DAL = 6.66 ± 0.77 hours), urinary indices (specific gravity, color), body mass change (D(TT) = -2.22% ± 1.73%, DAL = -2.29% ± 1.62%), fluid intake (D(TT) = 5.63 ± 2.59 L/6.7 h, D(AL) = 6.04 ± 2.37 L/6.7 h), dietary energy intake, macronutrient intake, ratings of thirst (D(TT) start = 2 ± 1, D(TT) finish = 6 ± 1, DAL start = 2 ± 1, D(AL) finish = 6 ± 1), pain, perceived exertion, or thermal sensation. Total fluid intake on recovery day +1 was the primary significant difference (D(AL) = 5.13 ± 1.87 L/24 h, D(TT) = 3.13 ± 1.53 L/24 h, t18 = 2.59, P = .02). CONCLUSIONS Observations on event day indicated that drinking to thirst and drinking ad libitum resulted in similar physiologic and perceptual outcomes. This suggests that specific instructions to "drink to thirst" were unnecessary. Indeed, if athletes drink ad libitum, they can focus on training and competition rather than being distracted by ongoing evaluation of thirst sensations.
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Abstract
The aim of this current opinion article is to provide a contemporary perspective on the role of brain regulatory control of paced performances in response to exercise challenges. There has been considerable recent conjecture as to the role of the brain during exercise, and it is now broadly accepted that fatigue does not occur without brain involvement and that all voluntary activity is likely to be paced at some level by the brain according to individualised priorities and knowledge of personal capabilities. This article examines the role of pacing in managing and distributing effort to successfully accomplish physical tasks, while extending existing theories on the role of the brain as a central controller of performance. The opinion proposed in this article is that a central regulator operates to control exercise performance but achieves this without the requirement of an intelligent central governor located in the subconscious brain. It seems likely that brain regulation operates at different levels of awareness, such that minor homeostatic challenges are addressed automatically without conscious awareness, while larger metabolic disturbances attract conscious awareness and evoke a behavioural response. This supports the view that the brain regulates exercise performance but that the interpretation of the mechanisms underlying this effect have not yet been fully elucidated.
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Affiliation(s)
- A M Edwards
- Institute of Sport and Exercise Science, James Cook University, Cairns, QLD, Australia,
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Davis BA, Thigpen LK, Hornsby JH, Green JM, Coates TE, O'Neal EK. Hydration kinetics and 10-km outdoor running performance following 75% versus 150% between bout fluid replacement. Eur J Sport Sci 2014; 14:703-10. [PMID: 24697790 DOI: 10.1080/17461391.2014.894578] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Current American College of Sports Medicine (ACSM) guidelines recommend replacing 150% of sweat losses between training bouts separated by ≤12 hours, but little evidence exists concerning the implications of this strategy for runners. Participants (n = 13) in this study replaced 75% (1637 ± 372 mL) or 150% (3099 ± 850 mL) of sweat losses following an outdoor evening run (∼75 minutes; Wet-bulb-globe temperature (WBGT) = ∼27°C) and consumed a standardised evening meal and breakfast before completing an outdoor (WBGT = ∼23°C) 10-km time-trial the following morning. Urine was collected between runs and urine specific gravity (USG) was assessed pre-run. Significant differences were found in pre-run body mass (75% = 69.6 ± 9.2; 150% = 70.1 ± 9.3 kg; P = 0.02) and USG (75% = 1.026 ± 0.005; 150% = 1.014 ± 0.007; P < 0.001). Heart rate during 10-km run (168 ± 14 versus 168 ± 12 beats min(-1)) and post-run intestinal temperature (39.08 ± 0.52 versus 39.00 ± 0.70 °C) did not differ for 75% and 150%, respectively, despite an ∼3% performance improvement (75% = 47.28 ± 6.64; 150% = 45.93 ± 6.04 minutes; P = 0.001) due to a faster pace in the second half of the run with 150% replacement. Session rate of perceived exertion (RPE) was lower (P = 0.02) during 150% (7.5 ± 1.3) versus 75% (8.4 ± 0.9). Reluctant drinkers potentially hinder training quality between evening and morning runs in the heat, but copious urine production and difficulty in consuming recommended fluid volumes suggest fluid replacement <150% may be more ideal.
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Affiliation(s)
- Brett Alan Davis
- a Department of Health, Physical Education and Recreation , University of North Alabama , Florence , AL , USA
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Fleming J, James LJ. Repeated familiarisation with hypohydration attenuates the performance decrement caused by hypohydration during treadmill running. Appl Physiol Nutr Metab 2014; 39:124-9. [DOI: 10.1139/apnm-2013-0044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examined the effect of repeated familiarisation to hypohydration on hypohydrated exercise performance. After familiarisation with the exercise protocol, 10 recreationally active males completed a euhydrated (EU-pre) and hypohydrated (HYPO-pre) trial, which involved a 45-min steady state run at 75% peak oxygen uptake (45SS) followed by a 5-km time trial (TT). Euhydration and hypohydration were induced by manipulating fluid intake in the 24-h pre-exercise and during the 45SS. Subjects then completed 4 habituation sessions that involved replication of the HYPO-pre trial, except they completed 60 min of running at 75% peak oxygen uptake and no TT. Subjects then replicated the euhydrated (EU-post) and hypohydrated (HYPO-post) trials. Body mass loss pre-TT was 0.2 (0.2)% (EU-pre), 2.4 (0.3)% (HYPO-pre), 0.1 (0.1)% (EU-post), and 2.4 (0.3)% (HYPO-post). TT performance was 5.8 (2.4)% slower during the HYPO-pre trial (1459 (250) s) than during the EU-pre trial (1381 (237) s) (p < 0.01), but only 1.2 (1.6)% slower during the HYPO-post trial (1381 (200) s) than during the EU-post trial (1366 (211) s) (p = 0.064). TT performance was not different between EU-pre and EU-post trials, but was 5.1 (2.3)% faster during the HYPO-post trial than the HYPO-pre trial (p < 0.01). Heart rate was greater during HYPO trials than EU trials (p < 0.001), whilst rating of perceived exertion (RPE) response was similar to TT time and was lower in the HYPO-post trial than the HYPO-pre trial (p < 0.01). In conclusion, hypohydration impaired 5-km running performance in subjects unfamiliar with the hypohydration protocol, but 4 familiarisation sessions designed to habituate subjects with the hypohydration protocol attenuated the performance decrement, seemingly via an attenuation of RPE during hypohydrated exercise.
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Affiliation(s)
- Joseph Fleming
- SHAPE Research Group, School of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Lewis J. James
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- SHAPE Research Group, School of Science and Technology, Nottingham Trent University, Nottingham, UK
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Kavouras SA, Bardis CN. Response. Med Sci Sports Exerc 2014; 46:208. [DOI: 10.1249/mss.0000000000000163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Goulet EDB, Dion T, Savoie FA. Does Mild Hypohydration Really Reduce Cycling Endurance Performance in the Heat? Med Sci Sports Exerc 2014; 46:207. [DOI: 10.1249/mss.0b013e3182a17c0e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Dion T, Savoie FA, Asselin A, Gariepy C, Goulet EDB. Half-marathon running performance is not improved by a rate of fluid intake above that dictated by thirst sensation in trained distance runners. Eur J Appl Physiol 2013; 113:3011-20. [DOI: 10.1007/s00421-013-2730-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 09/14/2013] [Indexed: 10/26/2022]
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Hillman AR, Turner MC, Peart DJ, Bray JW, Taylor L, McNaughton LR, Siegler JC. A Comparison of Hyperhydration Versus Ad Libitum Fluid Intake Strategies on Measures of Oxidative Stress, Thermoregulation, and Performance. Res Sports Med 2013; 21:305-17. [DOI: 10.1080/15438627.2013.825796] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Angela R. Hillman
- a Department of Health and Physical Education , Marywood University , Scranton , Pennsylvania , USA
- b Department of Sport, Health & Exercise Science , The University of Hull , Hull , United Kingdom
| | - Mark C. Turner
- c School of Sport, Exercise and Health Sciences , Loughborough University , Loughborough , United Kingdom
| | - Daniel J. Peart
- b Department of Sport, Health & Exercise Science , The University of Hull , Hull , United Kingdom
| | - James W. Bray
- b Department of Sport, Health & Exercise Science , The University of Hull , Hull , United Kingdom
| | - Lee Taylor
- d Department of Sport and Exercise Sciences , Institute of Sport and Physical Activity Research (ISPAR), The University of Bedfordshire , Bedford , United Kingdom
| | - Lars R. McNaughton
- e Sport and Physical Activity Department , Edge Hill University , Ormskirk , United Kingdom
| | - Jason C. Siegler
- f School of Biomedical and Health Sciences , University of Western Sydney, Campbelltown Campus , Penrith , Australia
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Effects of isolated locomotor muscle fatigue on pacing and time trial performance. Eur J Appl Physiol 2013; 113:2371-80. [PMID: 23756830 DOI: 10.1007/s00421-013-2673-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 05/30/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE Locomotor muscle fatigue impairs exercise performance during time to exhaustion tests. However, its effect on self-regulation of power output (pacing) is unknown. The primary aim of this study was to investigate the effects of locomotor muscle fatigue on pacing and time trial performance. METHODS Ten healthy recreationally active men completed a 15-min time trial on a cycle ergometer 30 min after undergoing an eccentric fatiguing protocol designed to induce a substantial strength loss in the knee extensor muscles without inducing significant metabolic stress. This fatigue condition was compared with a control condition, using a randomly counterbalanced AB/BA crossover design. RESULTS Total work completed during the 15-min cycling time trial was significantly reduced by 4.8 % in the fatigue condition compared with the control condition. This was caused by a significant reduction in power output. Rating of perceived exertion was significantly higher in the fatigue condition compared with the control condition only during the first 3 min of the time trial. Heart rate and vastus lateralis integrated electromyogram were not significantly different between the two conditions. CONCLUSION The results show that participants with fatigued locomotor muscles reduce their pace but do not change their pacing strategy. As a result, there was a significant reduction in time trial performance. As predicted by the psychobiological model of exercise performance, a slower pace may be a behavioral response to compensate for the significant increase in perception of effort induced by locomotor muscle fatigue.
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Rüst CA, Knechtle B, Knechtle P, Wirth A, Rosemann T. Body mass change and ultraendurance performance: a decrease in body mass is associated with an increased running speed in male 100-km ultramarathoners. J Strength Cond Res 2012; 26:1505-16. [PMID: 22614141 DOI: 10.1519/jsc.0b013e318231a7b5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We investigated, in 50 recreational male ultrarunners, the changes in body mass, selected hematological and urine parameters, and fluid intake during a 100-km ultramarathon. The athletes lost (mean and SD) 2.6 (1.8) % in body mass (p < 0.0001). Running speed was significantly and negatively related to the change in body mass (p < 0.05). Serum sodium concentration ([Na⁺]) and the concentration of aldosterone increased with increasing loss in body mass (p < 0.05). Urine-specific gravity increased (p < 0.0001). The change in body mass was significantly and negatively related to postrace serum [Na⁺] (p < 0.05). Fluid intake was significantly and positively related to both running speed (r = 0.33, p = 0.0182) and the change in body mass (r = 0.44, p = 0.0014) and significantly and negatively to both postrace serum [Na⁺] (r = -0.42, p = 0.0022) and the change in serum [Na⁺] (r = -0.38, p = 0.0072). This field study showed that recreational, male, 100-km ultramarathoners dehydrated as evidenced by the decrease in >2 % body mass and the increase in urine-specific gravity. Race performance, however, was not impaired because of the loss in body mass. In contrast, faster athletes lost more body mass compared with slower athletes while also drinking more. The concept that a loss of >2% in body mass leads to dehydration and consequently impairs endurance performance must be questioned for ultraendurance athletes competing in the field. For practical applications, a loss in body mass during a 100-km ultramarathon was associated with a faster running speed.
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Affiliation(s)
- Christoph A Rüst
- Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland
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Gigou PY, Dion T, Asselin A, Berrigan F, Goulet EDB. Pre-exercise hyperhydration-induced bodyweight gain does not alter prolonged treadmill running time-trial performance in warm ambient conditions. Nutrients 2012; 4:949-66. [PMID: 23016126 PMCID: PMC3448081 DOI: 10.3390/nu4080949] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/17/2012] [Accepted: 08/07/2012] [Indexed: 11/16/2022] Open
Abstract
This study compared the effect of pre-exercise hyperhydration (PEH) and pre-exercise euhydration (PEE) upon treadmill running time-trial (TT) performance in the heat. Six highly trained runners or triathletes underwent two 18 km TT runs (~28 °C, 25%–30% RH) on a motorized treadmill, in a randomized, crossover fashion, while being euhydrated or after hyperhydration with 26 mL/kg bodyweight (BW) of a 130 mmol/L sodium solution. Subjects then ran four successive 4.5 km blocks alternating between 2.5 km at 1% and 2 km at 6% gradient, while drinking a total of 7 mL/kg BW of a 6% sports drink solution (Gatorade, USA). PEH increased BW by 1.00 ± 0.34 kg (P < 0.01) and, compared with PEE, reduced BW loss from 3.1% ± 0.3% (EUH) to 1.4% ± 0.4% (HYP) (P < 0.01) during exercise. Running TT time did not differ between groups (PEH: 85.6 ± 11.6 min; PEE: 85.3 ± 9.6 min, P = 0.82). Heart rate (5 ± 1 beats/min) and rectal (0.3 ± 0.1 °C) and body (0.2 ± 0.1 °C) temperatures of PEE were higher than those of PEH (P < 0.05). There was no significant difference in abdominal discomfort and perceived exertion or heat stress between groups. Our results suggest that pre-exercise sodium-induced hyperhydration of a magnitude of 1 L does not alter 80–90 min running TT performance under warm conditions in highly-trained runners drinking ~500 mL sports drink during exercise.
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Affiliation(s)
- Pierre-Yves Gigou
- Research Centre on Aging, University of Sherbrooke, Sherbrooke, PQ J1H 4C4, Canada; (P.-Y.G.); (T.D.); (A.A.)
- Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada;
| | - Tommy Dion
- Research Centre on Aging, University of Sherbrooke, Sherbrooke, PQ J1H 4C4, Canada; (P.-Y.G.); (T.D.); (A.A.)
- Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada;
| | - Audrey Asselin
- Research Centre on Aging, University of Sherbrooke, Sherbrooke, PQ J1H 4C4, Canada; (P.-Y.G.); (T.D.); (A.A.)
- Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada;
| | - Felix Berrigan
- Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada;
| | - Eric D. B. Goulet
- Research Centre on Aging, University of Sherbrooke, Sherbrooke, PQ J1H 4C4, Canada; (P.-Y.G.); (T.D.); (A.A.)
- Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada;
- Author to whom correspondence should be addressed; ; Tel.: +1-819-780-2220 (ext. 45226); Fax: +1-819-829-7141
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